en عمومی General پژوهشي Original Research <span style="font-size:14px;"><span style="font-family:Tahoma;"><strong>Background</strong>: Pseudomonas aeruginosa biofilm is one of the problems in antibiotic treatment of infections. Nanomedicines, such as chitosan (CS) can carry multiple drugs and improve the therapeutic effects of antibiotics.<br> <strong>Objectives</strong>: This study aimed at the synthesis and characterization of ciprofloxacin-loaded chitosan nanoparticles for eradication of P. aeroginosa biofilm.<br> <strong>Methods</strong>: Cipro-CS microparticles were prepared by ionic gelation method and their size, zeta potential, and drug release pattern were determined. MBEC and MBIC of different groups of antibiotics (ciprofloxacin, ciprofloxacin-PA&beta;N, CS ciprofloxacin, and CS ciprofloxacin-PA&beta;N) were performed on biofilm samples of P. aeroginosa.&nbsp;<br> <strong>Results</strong>: Ciprofloxacin loading efficiency was 35.51%, and encapsulation efficiency was 55.06%. Released ciprofloxacin from CS nanoparticles was 80% after 24 hours. Biofilm production was positive in 96.7% of the isolates while 30.1% of the samples had strong biofilm. The best result for MBIC was CS ciprofloxacin, CS ciprofloxacin-PA&beta;N, ciprofloxacin- PA&beta;N, and ciprofloxacin, respectively. For MBEC the result was slightly different and from the best to better CS Ciprofloxacin-PA&beta;N, CS Ciprofloxacin, Ciprofloxacin-PA&beta;N, and ciprofloxacin.<br> <strong>Conclusion</strong>: Today, with increasing antibiotic resistance, there are many challenges in treating infections. Due to the role of biofilm in antibiotic resistance, researchers are looking for new antibiotics to treat infections.</span></span> Chitosan, Nanoparticle, Biofilm, Pseudomonas aeruginosa 243 258 http://pbr.mazums.ac.ir/browse.php?a_code=A-10-1112-1&slc_lang=en&sid=1 Foroogh Faridi faridi865@yahoo.com 100319475328460010331 100319475328460010331 No Department of Microbiology, Faculty of Science, Agriculture and New Technologies, Shiraz Branch, Islamic Azad University, Shiraz, Iran. Nima Bahador nimabahador22@gmail.com 100319475328460010332 100319475328460010332 Yes Department of Microbiology, Faculty of Science, Agriculture and New Technologies, Shiraz Branch, Islamic Azad University, Shiraz, Iran. Saeed Shoja shojasaeed@gmail.com 100319475328460010333 100319475328460010333 No Infectious and Tropical Diseases Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran. Sahar Abbasi sab656@gmail.com 100319475328460010334 100319475328460010334 No Department of Pharmaceutics, Faculty of Pharmacy, Hormozgan University of Medical Sciences, Bandar Abbas, Iran.